The present invention relates to compositions for melting ice on surfaces such as streets, parking lots, sidewalks, etc.
There are many products now used for melting ice and snow. These products can be, but are not limited to, hygroscopic salts such as calcium chloride and magnesium chloride; fertilizers such as potassium chloride and urea; and rock salt and non-slip aggregates like sand, cinders and calcined diatomaceous earth absorbents.
These current commercial products have their advantages and disadvantages. For example, the hygroscopic salts are excellent low-temperature melters but are expensive. Fertilizers cause minimal problems on runoff as they will aid surrounding vegetation, but as ice melters they have poor melting characteristics. Rock salt is inexpensive, but will kill vegetation on heavy runoff and has poor ice melting properties. Aggregates, like sand, do not melt or solubilize, and therefore have difficulty embedding into ice to provide a non-slip surface.
To address some of these disadvantages, blends have been employed, but often each ingredient acts independently with little to no synergistic effect. Agglomerates such as shown in our previous U.S. Pat. No. 5,211,869 issued May 18, 1993, the disclosure of which is incorporated herein by reference, have been successful, but they are complex and expensive in their manufacture and are limited in their ability to synergistically coact with a wide range of base materials. These issues have limited the use of agglomerates.
Accordingly, there is a continuing need for a new ice melting composition, and methods for making same, which allows for a coacting synergistic relationship between the ingredients to provide a commercially acceptable, flowable product at economic prices, and which provides a product that effectively allows good ice melt, favorable abrasion or grip properties and which avoids undesirable environmental problems caused by runoff, such as vegetation kill.
It goes without saying that reducing complexity of process of making blended ice melters also reduces expense providing savings to the ultimate consumer.
Our previous patents: U.S. Pat. No. 5,599,475 issued Feb. 4, 1997; U.S. Pat. No. 5,651,915 issued Jul. 29, 1997 and U.S. Pat. No. 5,683,619 issued Nov. 4, 1997, the disclosure of which are incorporated herein by reference have been successful but they too are complex in their manufacture. The above patents cover a process wherein urea is coated with a potassium acetate solution. Calcium chloride powder is then added as a separate ingredient to the urea to form a coating in a quick mix process. After this process the coated urea particles are blended with calcium chloride pellets. This final product is put through a screening process to pull off excess calcium chloride powder from the process before packaging. There is a need to eliminate at least some of the multiple steps in this process while still producing the calcium chloride coating on the urea portion of the mixture.
In the present process, some of the similar ingredients are used as in our previous patents but processing steps are eliminated. In particular, the current process, when compared with for example U.S. Pat. No. 5,651,915, eliminates a screening process and allows for simultaneous crumbling of calcium chloride pellets into powder and coating with the powder, thus eliminating some of the multiple steps of U.S. Pat. No. 5,651,915.
The method and manner of accomplishing this primary need is the objective of this invention. Accomplishing this and other objectives will be apparent from the description below.